DRX Carrier Aggregation PDCCH Monitoring
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Solution Overview
Problem
In LTE systems, carrier aggregation introduces challenges in battery efficiency due to the need to monitor multiple component carriers for control and data channels, leading to increased battery consumption and complexity in maintaining time relationships between PDCCH and PDSCH transmissions.
Innovation Solution
Implementing a method for wireless transmit/receive units (WTRUs) to operate in discontinuous reception (DRX) mode using carrier aggregation, where PDCCH and PDSCH active times are defined on a per-carrier basis, allowing independent DRX operation for each component carrier, and enabling synchronization or asynchronous operation based on specific timers and configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PDCCH and PDSCH are transmitted on different component carriers in carrier aggregation, then system flexibility and capacity are improved, but battery consumption increases due to the need to monitor multiple carriers
Solution Approach 1:
The patent segments the monitoring task by dividing component carriers into two subsets: a first subset configured for PDCCH reception and a second subset not configured for PDCCH reception. The WTRU monitors PDCCH only on carriers in the first subset, while PDSCH can be transmitted on carriers in either subset. This segmentation allows the system to maintain flexibility in PDSCH transmission while reducing battery consumption by limiting PDCCH monitoring to specific carriers.
2Stability of the object's composition
If PDCCH and PDSCH are transmitted in the same subframe, then time relationship is maintained, but battery consumption increases due to continuous monitoring requirements
Solution Approach 1:
The patent applies preliminary action by configuring the WTRU with advance knowledge of which component carriers are designated for PDCCH reception versus PDSCH transmission only. This pre-configuration allows the WTRU to prepare monitoring schedules in advance, knowing exactly when and where to expect PDCCH transmissions, thereby maintaining stable time relationships while avoiding continuous monitoring of all carriers.
3Reliability
If PDCCH monitoring is performed on multiple component carriers, then DL assignment reception is improved, but device complexity increases
Solution Approach 1:
The patent segments the set of component carriers into distinct subsets with specific functions: the first subset is configured for PDCCH reception while the second subset is configured for PDSCH reception only. This segmentation simplifies the monitoring complexity by providing clear rules for the WTRU: monitor PDCCH only on carriers in the first subset, and monitor PDSCH on carriers in both subsets. This structured approach maintains reliable DL assignment reception while reducing the complexity of determining which carriers to monitor.
Data Source
AI summary
Methods and apparatus are described. A long term evolution-advanced (LTE-A) wireless transmit/receive unit (WTRU) includes a transceiver and a processor. The transceiver receives discontinuous reception (DRX) configuration information. The processor, in response to the received DRX information, controls the transceiver to monitor LTE-A physical downlink control channels (PDCCHs) in subframes in a first frequency band during an active time. The processor further, in response to detecting a downlink assignment in an LTE-A PDCCH in the first frequency band during the active time, wherein the downlink assignment indicates a second frequency band and assigned subcarriers within the second frequency band, to receive an LTE-A physical downlink shared channel (PDSCH) K subframes after a transmission of the downlink assignment. The second frequency band is different than the first frequency band.